1. Field of the Invention
This invention relates to a power distribution apparatus, and more particularly, to an improved vertical riser bus bar arrangement, an improved insulated brace arrangement, and an improved barrier arrangement.
2. Description of the Prior Art
In a switchboard or switch gear of a power distribution apparatus, a vertical riser arrangement distributes three phase power down a vertical stack of circuit breakers. The power rating capacity is determined, in part, by the design of the vertical riser bus bar arrangement.
Current vertical riser designs which may be employed in a motor control center may consist of a flat, rectangular member whose electrical capacity may be increased by attaching one or more metal bars in surface-to-surface contact with the horizontal member. An example is disclosed in U.S. Pat. No. 4,178,624 issuing on Dec. 11, 1979, in which one of the inventors is the inventor of the present invention. Another vertical riser bus bar arrangement, which may be used in a power distribution apparatus, in which the present invention may be employed, may consist of two or more spaced apart straight metal bars.
These current vertical bus bar arrangements are more likely to generate less current rating capacity per cross sectional square inch, and have insufficient surface area for cooling purposes.
Present vertical riser bus bar arrangements may include two barrier members which are in surface to surface contact with the bus bar arrangement, and which are held together by two horizontal brace members bolted together and fastened in the enclosure for the bus bar arrangement. The barrier members are made of an electrical insulating material, extend between each phase of the bus bar arrangement in a labyrinth fashion, and extend coextensively to encase the bus bar arrangement. Such an example for the barrier members and the brace members is disclosed in the aforesaid U.S. Pat. No. 4,178,624.
A power distribution apparatus employing the invention may have a current capacity ranging from 600 to 5,000 amperes. It receives its power from a substation with a current capacity ranging from 4,100 to 13,000 amperes, and directs power to a load center such as a motor control center of U.S. Pat. No. 4,178,624, having a current range of 100 to 2,000 amperes.
In a power distribution apparatus, a barrier arrangement encasing the vertical bus bar arrangement may or may not be used. If a barrier arrangement is used and is designed similar to that disclosed in U.S. Pat. No. 4,178,624, the barrier members extend between the brace arrangement and vertical bus bar arrangement, to provide insulation between the brace and bus bar arrangement which typically are made of metal. If no barrier arrangement is used, then there still must be some type of insulation between the brace and vertical bus bar arrangements. This insulation must be strong enough to withstand short circuit withstand ratings of 100KA to 200KA for 600 volt equipment, and must be designed to allow for the use of a barrier arrangement, if desired.
In a vertical bus bar arrangement of a power distribution apparatus, the electrical connections are made through stabs on the line side, and runbacks on the load side connected to the circuit breakers, and one or more crossbars located on the side of the vertical bus bar arrangement opposite to the circuit breakers. To distribute the three phase power to adjacent enclosures, a barrier arrangement must be designed to accommodate for these several electrical connections and still provide a complete encasement of the vertical bus bar arrangement and sufficient isolation between each of the three phases of the bus bar arrangement.
There is a real need to provide a vertical bus bar arrangement which has an increased current rating per cross sectional square inch with more surface area for cooling capacity.
There is also a need to provide a brace arrangement which is insulated from the vertical bus bar arrangement regardless of whether a barrier arrangement is used or not used, and which is strong enough to withstand the short circuit withstand ratings.